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991.
Monika Bosacka Anna Błońska-Tabero Elżbieta Filipek Jana Luxova Petra Šulcová 《Journal of Thermal Analysis and Calorimetry》2017,130(1):95-101
A new dichromium(III) cobalt(II) diphosphate(V) of the formula CoCr2(P2O7)2 was detected in the Co3Cr4(PO4)6–Cr(PO3)3 system. The new compound was obtained as a result of high-temperature solid-state reactions between CoCO3, Cr2O3 and (NH4)2HPO4 as well as between Cr(PO3)3 and Co3Cr4(PO4)6. CoCr2(P2O7)2 was characterized using XRD, DTA and IR methods. Results demonstrated that CoCr2(P2O7)2 crystallizes in the triclinic system and its unit cell parameters were calculated. Its infrared spectrum was presented. CoCr2(P2O7)2 melts incongruently at 1270±10 °C with a formation of solid α-CrPO4. The compound Co3Cr4(PO4)6, component of the system under study, was obtained for the first time as a pure phase. Its thermal stability was also investigated. Co3Cr4(PO4)6 is stable in air up to 1410 ± 20 °C. 相似文献
992.
Dr. Monika Schmidt M. Sc. David Konieczny Dr. Eugenia V. Peresypkina Dr. Alexander V. Virovets Dr. Gabor Balázs Dr. Michael Bodensteiner M. Sc. Felix Riedlberger Dr. Hannes Krauss Prof. Dr. Manfred Scheer 《Angewandte Chemie (International ed. in English)》2017,56(25):7307-7311
The redox chemistry of [Cp*Fe(η5-As5)] ( 1 , Cp*=η5-C5Me5) has been investigated by cyclic voltammetry, revealing a redox behavior similar to that of its lighter congener [Cp*Fe(η5-P5)]. However, the subsequent chemical reduction of 1 by KH led to the formation of a mixture of novel Asn scaffolds with n up to 18 that are stabilized only by [Cp*Fe] fragments. These include the arsenic-poor triple-decker complex [K(dme)2][{Cp*Fe(μ,η2:2-As2)}2] ( 2 ) and the arsenic-rich complexes [K(dme)3]2[(Cp*Fe)2(μ,η4:4-As10)] ( 3 ), [K(dme)2]2[(Cp*Fe)2(μ,η2:2:2:2-As14)] ( 4 ), and [K(dme)3]2[(Cp*Fe)4(μ4,η4:3:3:2:2:1:1-As18)] ( 5 ). Compound 4 and the polyarsenide complex 5 are the largest anionic Asn ligand complexes reported thus far. Complexes 2 – 5 were characterized by single-crystal X-ray diffraction, 1H NMR spectroscopy, EPR spectroscopy ( 2 ), and mass spectrometry. Furthermore, DFT calculations showed that the intermediate [Cp*Fe(η5-As5)]−, which is presumably formed first, undergoes fast dimerization to the dianion [(Cp*Fe)2(μ,η4:4-As10)]2−. 相似文献
993.
Let {Z u = ((εu, i, j))p×n} be random matrices where {εu, i, j} are independently distributed. Suppose {A i }, {B i } are non-random matrices of order p × p and n × n respectively. Consider all p × p random matrix polynomials \(P = \prod\nolimits_{i = 1}^{k_l } {\left( {n^{ - 1} A_{t_i } Z_{j_i } B_{s_i } Z_{j_i }^* } \right)A_{t_{k_l + 1} } }\). We show that under appropriate conditions on the above matrices, the elements of the non-commutative *-probability space Span {P} with state p?1ETr converge. As a by-product, we also show that the limiting spectral distribution of any self-adjoint polynomial in Span{P} exists almost surely. 相似文献
994.
We prove results on the asymptotic behavior of solutions to discrete-velocity models of the Boltzmann equation in the one-dimensional slab 0x<1 with=" general=" stochastic=" boundary=" conditions=" at=" x="0" and=" x="1." assuming=" that=" there=" is=" a=" constant=">1>wall Maxwellian M=(M
i) compatible with the boundary conditions, and under a technical assumption meaning strong thermalization at the boundaries, we prove three types of results:
Communicated by L. Arkeryd 相似文献
I. | If no velocity has x-component 0, there are real-valued functions 1(t) and 2(t) such that in a measure-theoretic sense f i(0, t) 1 (t)M i , f i(1, t) 2 (t)M i as t. 1 and 2 are closely related and satisfy functional equations which suggest that 1(t)1 and 2(t)1 as t. |
II. | Under the additional assumption that there is at least one non-trivial collision term containing a product f k f l with k = l , where k denotes the x-component of the velocity associated with f k , we show that in a measure-theoretic sense 1(t) and 2(t) converge to 1 as t. This entails L 1-convergence of the solution to the unique wall Maxwellian. For this result, k = l =0 is admissible. |
III. | In the absence of any collision terms, but under the assumption that there is an irrational quotient ( i +¦ j ¦)/( l +¦ k ¦) (here i , l >0 and j , k <0), renewal=" theory=" entails=" that=" the=" solution=" converges=" to=" the=" unique=" wall=" maxwellian=" in=">0),>L . |
995.
Mica Cabrera Faizah Taher Alendre Llantada Quyen Do Tyeshia Sapp Monika Sommerhalter 《Molecules (Basel, Switzerland)》2021,26(12)
The health benefits of green tea are associated with its high catechin content. In scientific studies, green tea is often prepared with deionized water. However, casual consumers will simply use their local tap water, which differs in alkalinity and mineral content depending on the region. To assess the effect of water hardness on catechin and caffeine content, green tea infusions were prepared with synthetic freshwater in five different hardness levels, a sodium bicarbonate solution, a mineral salt solution, and deionized water. HPLC analysis was performed with a superficially porous pentafluorophenyl column. As water hardness increased, total catechin yield decreased. This was mostly due to the autoxidation of epigallocatechin (EGC) and epigallocatechin gallate (EGCG). Epicatechin (EC), epicatechin gallate (ECG), and caffeine showed greater chemical stability. Autoxidation was promoted by alkaline conditions and resulted in the browning of the green tea infusions. High levels of alkaline sodium bicarbonate found in hard water can render some tap waters unsuitable for green tea preparation. 相似文献
996.
Anna Nowak Krystyna Cybulska Edyta Makuch ukasz Kucharski Monika Rewicka-Czabaska Piotr Prowans Norbert Czapla Piotr Bargiel Jan Petriczko Adam Klimowicz 《Molecules (Basel, Switzerland)》2021,26(2)
Epilobium angustifolium L. is applied as an antiseptic agent in the treatment of skin diseases. However, there is a lack of information on human skin penetration of active ingredients with antioxidative potential. It seems crucial because bacterial infections of skin and subcutaneous tissue are common and partly depend on oxidative stress. Therefore, we evaluated in vitro human skin penetration of fireweed ethanol-water extracts (FEEs) by determining antioxidant activity of these extracts before and after penetration study using 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and Folin–Ciocalteu methods. Microbiological tests of extracts were done. The qualitative and quantitative evaluation was performed using gas chromatography-mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC-UV) methods. The in vitro human skin penetration using the Franz diffusion chamber was assessed. The high antioxidant activity of FEEs was found. Gallic acid (GA), chlorogenic acid (ChA), 3,4-dihydroxybenzoic acid (3,4-DHB), 4-hydroxybenzoic acid (4-HB), and caffeic acid (CA) were identified in the extracts. The antibacterial activities were found against Serratia lutea, S. marcescens, Bacillus subtilis, B. pseudomycoides, and B. thuringiensis and next Enterococcus faecalis, E. faecium, Streptococcus pneumoniae, Pseudomonas aeruginosa, and P. fluorescens strains. In vitro penetration studies showed the penetration of some phenolic acids and their accumulation in the skin. Our results confirm the importance of skin penetration studies to guarantee the efficacy of formulations containing E. angustifolium extracts. 相似文献
997.
Monika Kdzierska-Matysek Magorzata Stryjecka Anna Teter Piotr Skaecki Piotr Domaradzki Mariusz Florek 《Molecules (Basel, Switzerland)》2021,26(6)
The study compared the content of eight phenolic acids and four flavonoids and the antioxidant activity of six Polish varietal honeys. An attempt was also made to determine the correlations between the antioxidant parameters of the honeys and their polyphenol profile using principal component analysis. Total phenolic content (TPC), total flavonoid content (TFC), antioxidant activity (ABTS) and reduction capacity (FRAP) were determined spectrophotometrically, and the phenolic compounds were determined using high-performance liquid chromatography (HPLC). The buckwheat honeys showed the strongest antioxidant activity, most likely because they had the highest concentrations of total phenols, total flavonoids, p-hydroxybenzoic acid, caffeic acid, p-coumaric acid, vanillic acid and chrysin. The principal component analysis (PCA) of the data showed significant relationships between the botanic origin of the honey, the total content of phenolic compounds and flavonoids and the antioxidant activity of the six Polish varietal honeys. The strongest, significant correlations were shown for parameters of antioxidant activity and TPC, TFC, p-hydroxybenzoic acid, caffeic acid and p-coumaric acid. Analysis of four principal components (explaining 86.9% of the total variance), as a classification tool, confirmed the distinctiveness of the Polish honeys in terms of their antioxidant activity and content of phenolic compounds. 相似文献
998.
Jokanović Vukoman Vilotijević Miroljub Čolović Božana Jenko Monika Anžel Ivan Rudolf Rebeka 《Plasma Chemistry and Plasma Processing》2015,35(1):1-19
Plasma Chemistry and Plasma Processing - Hydroxyapatite (HA) coatings were deposited on high purity titanium substrate by atmospheric plasma spraying (APS) with high electric energy input.... 相似文献
999.
Joanna Kowalska Katarzyna Kińska Monika Sadowska Magdalena Biesaga Beata Krasnodębska-Ostręga 《International journal of environmental analytical chemistry》2015,95(12):1148-1156
Phytochelatins (PCs) play an important role in the detoxification and homeostasis processes in plants, since xenobiotics complexed by sulfhydryl groups are less toxic than the free ions. This paper describes studies related to PCs synthesis in Sinapis alba L. exposed to As and Tl salts, and in particular to the identification of the PC complexes that are formed in white mustard tissues. To reach the goal, two analytical methods were applied – high-performance liquid chromatography with fluorescent detection analysis after derivatisation of thiol compounds and high-performance liquid chromatography with electrospray ionization mass spectrometry (HPLC ESI MS). The study confirmed the synthesis of PCs in all plant organs under the influence of As salt. Moreover two As-PC complexes were identified: As-PC3 and As-PC4. While in the case of Tl – although that element strongly influenced the growth of Sinapis alba L. and to a great extent was transported to above-ground organs – no PC complexes or free PCs were found in plants exposed to Tl salt. Although both elements exist in mustard plant tissues at their trivalent oxidation state, showing high affinity to thiol groups, a defence mechanism associated with the synthesis of PC occurred only in case of arsenic. 相似文献
1000.
Matthias Ikeda Petr Tomeš Lukas Prochaska James Eilertsen Sascha Populoh Stefan Löffler Robert Svagera Monika Waas Herbert Sassik Anke Weidenkaff Silke Paschen 《无机化学与普通化学杂志》2015,641(11):2020-2028
Nano‐grained CoSb3 was prepared by melt‐spinning and subsequent spark plasma sintering. The phonon thermal conductivity of skutterudites is known to be sensitive to the kind and the amount of guest atoms. Thus, unfilled CoSb3 can serve as model compound to study the impact of a nanostructure on the thermoelectric properties, especially the phonon thermal conductivity. Therefore, a series of materials was prepared differing only by the cooling speed during the quenching procedure. In contrast to clathrates, the microstructure of meltspun CoSb3 was found to be sensitive to the cooling speed. Although the phonon thermal conductivity, studied by means of Flash and 3ω measurements, was found to be correlated with the grain size, the bulk density of the sintered materials had an even stronger impact. Interestingly, the reduced bulk density did not result in an increased electrical resistivity. The influence of Sb and CoSb2 as foreign phase on the electronic properties of CoSb3 was revealed by a multi‐band Hall effect analysis. While CoSb2 increases the charge carrier density, the influence of the highly mobile charge carriers introduced by elemental Sb on the thermoelectric properties of the composite offer an interesting perspective for the preparation of efficient thermoelectric composite materials. 相似文献